This much is known about Jennifer Spillman Martello’s ill-fated walk early Tuesday morning along Big Tree Road in Hamburg: The 29-year-old mother was on a narrow shoulder facing traffic, on a two-lane, unlighted road in the dead of night when she was apparently struck by a vehicle.

Martello was about 200 yards from her home on the other side of the road, headed away from the house where she lived with her husband and young daughter.

A passer-by called police at about 12:35 a.m. to say a body was alongside the road. When police got there, they found Martello unconscious with a serious head injury.

Police have said little since then, but her husband, Sam Martello, early Tuesday posted on Facebook that she was the victim of an “unknown ‘leaving-the-scene driver’ ” and then by midafternoon that she had died.

“This is very hard to write; but I have to express & honor her life, her soul & her spirit,” Martello wrote in a post at about 3 p.m. “She passed away to Heaven today on 7/15/2014 and ... she was my heartbeat and the most beautiful soul I have ever known. I ask that anyone and everyone pray for her & her family and her passing on ... I am barely keeping it together, but I have to be there for our 14-month-old baby, Amelia.”

Now police are trying to figure out what happened to her.

By all indications, Martello was struck by a vehicle, Hamburg police said. The details, however, remained very sketchy late Tuesday.

Police were alerted after the passer-by spotted Martello on Big Tree Road near Eagle-crest Mobile Home Park.

Police said her husband didn’t say why she was outside at the time but that he knows she was walking east on Big Tree.

Her Facebook status was updated early Tuesday morning by her husband in an earlier post, in which he said she was walking and was hit by a car and was “in a serious collision.” She suffered serious head trauma and during the morning hours had been listed in critical condition in the trauma intensive care unit in Erie County Medical Center.

Hamburg police confirmed that a vehicle was towed from a nearby residence in connection with the investigation but that it was returned to the owner and was not believed to have been involved in the incident.

Four police cars were parked outside of Martello’s duplex on the 3600 block of Big Tree Road at midmorning Tuesday. Hamburg police officers placed yellow markers about 200 yards away, on the north side of the road, where it appears Martello was found.

The road in that area has a narrow shoulder and no sidewalk. Investigators were pacing the area, apparently retracing Martello’s movements before she was hit.

The area where she was struck is just past a parking lot, several residences down from the Martellos’ home on the opposite side of the street.

Big Tree Road is a moderately busy country road that ends at McKinley Parkway. Because Martello was walking east, it is likely she was facing the car as it hit her.

One neighbor said Martello and her husband moved in about three months ago and said the couple had both been in a car accident recently and were still recovering.

“My guess is she wandered off. It’s kind of a mystery,” said the neighbor, who asked not to be identified. “I guess we’ll wait and see what the investigation shows. I don’t know her well, but she seemed like a sweet girl.”

Classmates.com states Martello, whose maiden name is Jennifer Spillman, graduated from Frontier High School in 2003.

Her Facebook page indicates she is a fan of the Bills, Sabres and New York Yankees, among other sports teams, in addition to classic rock, the “Twilight” movies and the television show “Two and A Half Men.”

Hamburg police said more information will be released when it becomes available.

Investigators urged anyone with information who can assist in the investigation to call the town Police Department at 648-5111, Ext. 2502.